Method of reduction of esters, etholides, glycerides



Patented Sept. 30, 1952 METHOD OF REDUCTION OF ESTERS,

ETHOLIDES, GLYCERIDES Paul-Angl aret, Ville DAvray, France Serial No.

No Drawing. Original application June 27, 1947,

757,661. Divided and this application January}, 1952, Serial No. 264,855. In

France July 5, 1946 This application is a division of my copending application Serial No. 757,661, filed June 27, 1947.

This invention relates to the reduction of esters, etholides, glycerides (glycerine esters), nitriles (alkyl cyanides) and the like. The method of the invention is particularly useful in the production of higher alcohols.

It has been common knowledge for a long time that theonly way for the chemical reduction of esters for the production of the alcohol corresponding to the acid of the ester is by the use of sodium and an alcohol.

However, this process often allows only a poor recovery of the alcohol (60 to 80 Various patents, that claim to give good results, advocate working under vacuum, under hydrogen pressure, or by adding the ester alcohol mixture in theoretical amount to the sodium dissolved in a suitable solvent. These processes, however, are never satisfactory as far as quantities (yields) are concerned, and exhibit various drawbacks in their procedure (use of pressure, vacuum, exceptional dissolving agents). Moreover, the possible glycerine recovery and the continuous operation are difficult.

The improvement introduced by this invention has as its main feature the decomposition of the alcoholate. formed in the reaction, by means of either one of two reagents which do not themselves react upon the sodium as such, under the conditions present in the reaction mass. But these reagents are capable, however, of regenerating the alcohol from the alcoholate, and act to precipitate the sodium in the form of a salt of high sodium content and which salt, however, does not add substantially to the viscosity of, the solution. The amount of alcohol in question is thus recovered in a satisfactory quantity, the decomposition of the alcoholate eliminating all secondary reactions that might prove detrimental to this result.

According to the reagent and alcohol employed, an exact degree of temperature, strength of solution and a definite working procedure must be put into service in order, on the one hand, to reach without difficulty the output required and, on the other-hand, to'use only the minimum amount of sodium.

Moreover, when the operation is .conducted in alcoholic solution, the use of any solvent, other than the alcohol, can be avoided. The sodium in small lumps can be added to the liquid esteralcohol mixture. The treatment is carried out at normal atmospheric pressure.

The process can be adapted to the same ma- 8 Claims. (Cl. 260-638) terials as the standard method of Bouveault and Blane. j

The decomposition of the alcoholate under the conditions indicated which constitutes the main object of this invention, can be effected in various ways and by various substances.

As a guide and not in any way binding, mention may be made especially of salts with acid reaction, e. g. NH-iCl, acid anhydrides, e. g. CO2, organic substances that can give various condensations with the alcoholate s for.,instance, chlorinated compounds in which the chlorine is especially unstable, substances that are able to convert the alcoholate merely by additive reaction. The ammonium salts which react. upon the alcoholate can give a reaction expressed as follows, in case X is a monovalent acid radical:

(R is the hydrocarbon radical of s. the alcohol which with sodium forms sodium'alcoholate, e. g. -C4H9). The acid radical can be'--C1, in the case of ammonium chloride.

The salts formed do not have more than a very slight solubility the alcohols. The CO2 reacts with the alcoholate, thus:

and the addition of water'causesthe following The salts formed do not havemorethan a very slight solubility in the lower alcohols; thus, COsNaz is practically insoluble, .butyl alcohol.

Generally speaking, it will be possible to use for this procedure all substances able to ensure, by particular reaction, the decomposition of the alcoholate, that, if present, is positively harmful for a satisfactory recovery in any amount as a result of the reaction, These bodies, however, under the conditions in which they are applied, must not give any secondaryreactions with the substances usually present or produced during the reaction '(ester, alcohol, sodium, nascent hydrogen) and the conversion of the alcoholate must proceed at a satisfactory rate.

Other advanta ii 9 the process are presented by the possibility that the process can he made continuous, the complete recovery of the glyc-. erine, the complete security and speed of the process. I I

The following examples of performanceof this invention may be submittedv asa' guide without any restricting clauses;

Example I.-Chemical agent for the decomposition of the alcoholate: ammonium chloride (NH4C1) Into a balloon-flask furnished with a downwardly extending condenser and with a mechanical agitator, is placed 100 gr. of whole oil (saponificatiodvalue: S. V.=135, iodine value, I. V.='75) and 200 to 300 gr. of anhydrous butanol (butyl alcohol). The temperature is kept at 100-115 C., so that the emission of ammonia (NI-I3) gradually draws oft the greater portion of the butyl alcohol. Then 27.5 gr. of sodium then washed until it is quite neutral, and dried.

(125% of the theoretical amount) cut up into" pieces, each weighing less than 1 gr., is added little .by little during agitation; 71 gr, of ammonium chloride is then added in fractional parts.

The sodium reacts on the butyl alcohol, forming sodium butylate, i. e.

When the ammonium chloride reacts with the sodium butylate, sodium chloride is formed, which being insoluble in butyl alcohol, precipitates C4H90Na+NHiCl:NaCl+C4I-I9OH. The ammonia gas liberated-mostly escapes through the condenser, and can be recovered, e. g. by absorption in HCl.Aq,-toreform ammonium chloride. P I

When the reaction is ended, the remaining butyl alcohol is distilled, then the heavy alcohols obtained by -'the reaction on the whale oil are washed with hot water. The hot water dissolves the sodium chloride and-"the glycerine liberated from the Whale oil; in the process. The recovery of glycerine'fromthe saline solution is an easy matter. I i

The resulting product, higher alcohol produced by the reduction of the fatty acids of the whale oil and also higher alcohol produced by saponification of the whale oil (which is partly glyceride esters of higher fatty acids, and partly esters of higher monohydric alcohols with such fatty acids) consistsof QQg-r. that, after treatment with a few drops of hydrochloric acid, washing and drying, has "acidity value: A. V.=1.5, S. V.=3.5, I. V.=6 '7, hydroxyl value: H. V.=224. The overall reaction can be expressed in a simple condensed form, as follows:

in which --COOR' is the fatty acid (or acids) of the whale 'oil (which is a mixture of esters and R is the'alkyl residue of such esters (whether monohydricor trihydric) Example II.Chemz'caZ reagent used for decomposition of alcoholate and precipitation of the sodium as a salt: carbon diomde (CO2 with H) In a balloon-flask of 1.5 litres capacity and of suitable shape, is added 200 gr. of butyl oleate and 400 to 600 gr. of butanol (butyl alcohol). Carbon dioxide is-beaten into the solution by means of a perforated hollow agitator; 66 gr. of sodium (an excess of cut up into pieces of less than 2 gr. each is added gradually. The temperature, starting at 80 C., rises steadily so as to reach the boiling point of the mixture at the end of the reaction. Water is added by degrees in some suitable shape (for instance, hydrated mineral salts) so that the mixture preserves a slight degree of viscosity. It will be understood that the hydrated mineral salts will Theresultant product consists of 155 gr. exhibiting the following characteristics: S. V.:3,

A. V.:0.8, I. V.= 80, 'hydroxyl value: H. V.:199.

.On treating rape-seed oil in the same manner (S. V.=177,' I. V.:105, A. V.:0.4) there is produced a product showing values: S. V.=3, A. .V=0.5, I. V.=105, hydroxyl value 187, but in this case it is necessary to add 40% excess of sodium, because the glycerine formed reacts on the sodium with partial loss or the latter. The recoveryof the glycerine presents no difificulty.

These processes are capableof-being. placed on.

a continuous basis. Fo'riinstance, by working with ammonium chloride added, .the -establish.-.

ment as a continuous procedure of Example No. 1 may be conducted in thefollowing Way:

The operation takes place in ahorizontal tube, with the agitator formed by a second tube revolving at high speed inside thefirst tube. Several (n) tubes in series are needed. l/n of the required amount of sodium is, added, at the front end of each tube, in pieces of which the diameter is slightly less than'the difference of the radii of tube and agitator. Theester-butanol mixture with its content of all @theammonium chloride is added at the front end oi? the first tube.

Between the outlet endof a tubeand inlet end of the following tube, .apo-rtion .of the butanol is distilled, so that at the end of the procedure the greater portionof the butanol has been removed. The-amounts of reagents used are nearly the same asin the non-continuous experimental run (i. e. in Example I).

The temperature of the first tube-is- C., the other tubes have successively higher temperatures, with temperatures in the last tube at C.

The number of tubes -is-a factor ofthe weight of sodium-pieces that thesize of theapparatus allows to be added. Thegreater the size of the apparatus, the smaller-the number of tubes required.

-On exit from the last tube, the normal work of distilling is carried. out, with washing. and decanting by continuous standard methods.

It may be observed that the starting mixture may be obtained directly bybringing the ammonia gases and hydrochloric acid gasinto the ester-butanol mixture, so that hydrochloric acid and sodium are the only reagents usedup.

The results obtained are as-good asinthe noncontinuousprocess. 7

It will thus 'be seen that the invention relates to improvements in the reduction of esters, etholides, glycerides, nitriles, etc., by means .of. an alkali metal, such as sodium. and. an alcohol: characterized by the fact that alkali'metal 8:100? holate produced by a side reaction isjdtgcomposed. By decomposing the alcoholate objectionablesecondary reactions are prevented. Dueto the, decomposition of the .alcoholate it is rendered harmless in the working of the process.

' The following additionaltexamples may be considered. They deal especially with improvements inrecoveries lowering of the amounts of lower alcohol, such as butyl alcohol, used and the,re-, duction of nitriles (alkyl cyanides) Example III .-Reduction of stearz'cmtrile Ammonium chloride in excess is added to the Example I V.(a) Reduction of pure butt/l oleate Into a balloon-flask furnished with a condenser, is placed 100 grams of butanol (butyl alcohol) and a fractional proportion to A) of the total amount (150 gr. for the particular example) of the butyl oleate to be reduced; about 55 gr. of sodium is added very slowly so that the total addition spreads over a period of several hours; for this reason, the reliability of the procedure is substantially increased in relation to other known methods.

After 1.5 gr. of sodium has been introduced, a continuous flow of water is directed into the mixture through the upper end of the condenser, so that the amount of water which has been added up to any instant during the reaction is slightly less than the theoretical amount required based on the amount of sodium which has been added up to that instant. The addition of water is continued until substantially the theoretical quantity (21 gr.) has been added. The overall reaction can be expressed as follows:

During this operation carbon dioxide and water are added in the respective required amount.

In the same way, the remainder of the oleate is added gradually. The temperature, starting at about 80 C., is raised slowly so as to reach at the end of the proceedings the boiling point of the medium.

When the reaction is completed, the required amount of hot water is added for dissolving the sodium carbonate formed: this can be done without any risk as the sodium has been completely converted; then the organic layer is decanted off and the butanol is separated out by distillationy Acidity value 1 Saponification value 7 Iodine value 22 Hydroxyl value 268 This last technique has the advantage over the previous examples by bringing into play only slight amounts of butanol, while allowing recovery of the glycerine to proceed.

The invention offers a number of advantages: When starting with chemically pure products, it

1 m .a,meth d forth production bf higher alcohol by the reaction of an ester of a higher fatty acid withrmetallic sodium and a substantiallyanhydrous lower aliphatic alcohol with resultant formation of a sodiumalcoholate, the improvement which comprises: carrying out said reaction at substantially atmospheric pressure; during said reaction, decomposing the sodium alcoholate substantially as fast as it is formed and regenerating said lower alcohol by addin during said reaction carbon dioxide and water; and maintaining during said reaction a temperature between about C. and the boiling temperature of the mixture of reactants and reaction products.

2. A method according to claim 1 in which said water is supplied by the Water of crystallization of a hydrated mineral salt which is inert toward said reactants and which does not modify the nature of the said reaction products.

3. A method according to claim 2 in which said hydrated mineral salt is sodium carbonate decahydrate. w

4. In a method for the production of higher alcohol by the reaction of an ester of a higher fatty acid with metallic sodium and a substantially anhydrous lower aliphatic alcohol with resultant formation of a sodium alcoholate, the improvement which comprises: carrying out said reaction at substantially atmospheric pressure; during said reaction, decomposing the sodium alcoholate substantially as fast as it is formed, and regenerating said lower alcohol by adding during said reaction carbon dioxide and water, and maintaining during said reaction a temperature between about 80 C. and the boiling temperature of the mixture of reactants and reaction products whereby the sodium salt produced by said reactron is substantially non-colloidal, is substantially insoluble in said lower alcohol, has a high sodium content and does not materially increase the viscosity of the mixture of products of said reaction. 5. In a method for the production of higher alcohol by the reaction of an ester of a higher fatty acid with metallic sodium and a substantially anhydrous lower aliphatic alcohol with resultant formation of a sodium alcoholatc, the improvement which comprises: carrying out said reaction at substantially atmospheric pressure; during said reaction, decomposing the sodium alcoholate substantially as fast as it is formed and regenerating said lower alcohol by adding during said reaction carbon dioxide and water, and maintaining during said reaction a temperature between about 80 C. and the boiling temperature of the mixture of reactants and reaction products thereby forming a non-viscous reaction,

product comprising said higher alcohol, unreacted portions of said lower alcohol, and a noncolloidal sodium salt having a high sodium content and insoluble in said lower alcohol.

6. A method according to claim 5, further comprising: separating'said sodium salt and unreacted 'ljower alcohol from said reaction product, and forming by j said separation a residue containing' said higher alcohol. I v I b 7. A method according to claim 6-, further comprising recovering a substantially pure higher alcohol from said residue. 7 t

8; In .a method for the production of oleic alcohol by the reaction ofbutyl oleate with metallic sodium in the presence of a substantially an-- hydrous lower aliphatic alcohol, the improvement which comprises: carrying out said reaction at substantially atmospheric pressure; during said reaction adding carbon dioxide and Water, and maintaining during said reaction a temperature between about 80 C. and the boiling temperature of the mixture or reactants and reactionproducts, whereby said lower alcohol is at least in part regenerated and whereby the sodium: Salt pro- 8 duced by said reaction is substantially non-colloidal, is substantially insoluble in said lower alcohol, has a high sodium content and does not materially increase the viscosity of the mixture of productsof said reaction. y

. A PAUL ANGLARE'I'.

-R'EFE- RENCES orrim 'I"he vfolloviiing references are of record in the file of this patent: I

UNITED STATES PATENTS Number 7 Name Date 1,971,742 Berts'ch 1 Aug} 28, 1934 2,563,044 Kamlet 1 Aug. 7, 1951 OTHER REFERENCES Anglare't et. a1.,'C0nip'te. Rendu, v01. 223, pp. 205-206 (1946). n 

1. IN A METHOD FOR THE PRODUCTION OF HIGHER ALCOHOL BY THE REACTION OF AN ESTER OF A HIGHER FATTY ACID WITH METALLIC SODIUM AND A SUBSTANTIALLY ANHYDROUS LOWER ALIPHATIC ALCOHOL WITH RESULTANT FORMATION OF A SODIUM ALCOHOLATE, THE IMPROVEMENT WHICH COMPRISES: CARRYING OUT SAID REACTION AT SUBSTANTIALLY ATMOSPHERIC PRESSURE; DURING SAID REACTION, DECOMPOSING THE SODIUM ALCOHOLATE SUBSTANTIALLY AS FAST AS IT IS FORMED AND REGENERATING SAID LOWER ALCOHOL BY ADDING DURING SAID REACTION, DECOMPOSING THE SODIUM AND MAINTAINING DURING SAID REACTION A TEMPERATURE BETWEEN ABOUT 80* C. AND THE BOILING TEMPERATURE OF THE MIXTURE OF REACTANTS AND REACTION 